An investigation of ductile fracture behavior of Ti6Al4V alloy fabricated by selective laser melting

To thoroughly understand the damage and fracture behavior of SLM-fabricated Ti6Al4V alloy, a number of tensile, compressive and torsional experiments covering various stress states were conducted with different types of the specimens. The effects of build directions (0 degrees, 45 degrees, 90 degrees) and post heat treatments (annealing and solution-aging) on the behavior were also studied. Metallographic tests were performed to draw out the connection between the material microstructures and mechanical performance, and fractographic analyses were carried out to elucidate the fracture modes and failure mechanisms. Compared with solution-aged material, the annealed material shows higher strength because of its smaller grain sizes of alpha + fl duplex microstructure. While the solution-aged material behaves more ductile than annealed one owing to the larger dislocation slip distance in fl phase matrix and the coordinating role of primary equiaxed alpha phases. The similarity of the microstructures under different build directions accounts for the insignificant anisotropy of the mechanical performance. Furthermore, a 3D fracture locus of SLM-fabricated Ti6Al4V alloy was constructed in the space of equivalent plastic strain at fracture, average stress triaxiality and the Lode angle parameter. (c) 2021 Elsevier B.V. All rights reserved.